温室地下滴灌灌水控制下限对番茄生长发育、果实品质和产量的影响

用温室小区试验的方法,通过对番茄株高和茎粗、果实品质和产量以及水分生产效率进行比较,探讨了温室栽培茄果类地下滴灌灌水控制下限的适宜取值范围。结果表明:在壤质土壤的试验地上,当地下滴灌管埋深为30 cm、计划湿润层深为15 cm~45 cm(厚度30 cm)、湿润比取0.7、灌水控制上限取田间持水量时,将土壤水吸力30 kPa作为控制灌水的下限,有利于番茄植株生长发育,可以达到高产、优质、节水的目的。     

不同城建绿地内PM2.5浓度季节变化及其与气象因子的关系

以杭州市临安区4种不同类型的城建绿地(居住区绿地、商业绿地、公共服务设施绿地和广场绿地)为研究对象,在2017年3月-2018年2月,采用实地测量法对绿地内的PM2.5浓度及气象因子(温度、相对湿度和风速)进行监测,研究城建绿地内PM2.5浓度的时空变化规律及其与气象因子的关系.结果表明,不同绿地的PM2.5浓度季节变...     

水盐胁迫下根系提水作用对土壤盐分与番茄产量的影响

为探究水盐胁迫下番茄根系发生提水作用的可能性及其对土壤盐分分布和番茄产量的影响,利用上下桶分根装置,设定上桶不同水分(W1、W2、W3表示土壤含水率为田间持水率的60%～70%、50%～60%、40%～50%)和盐分条件(S0、S1、S2表示Na Cl添加量分别为干土质量的0、0.2%、0.4%),监测分析了水盐胁迫下根系提水量、上桶盐分分布及番茄产量。结果表明:随着生育期的推进,根系提水量呈现先增加后减小的趋势,其中盐分对番茄根系提水量影响显著,在相同水分处理条件下,盐分含量越高,根系提水量越大;水盐胁迫下,上桶盐分含量与根系提水量呈线性正相关,除W1S0处理外,上桶土壤电导率在提水量达到最大时有所增加;与对照处理W1S0相比,水盐抑制了根系生长,使根系活性显著下降,同一水分处理下,随着盐分的增加,根长、根表面积及根体积减小;盐分对番茄水分生产率有显著影响,在相同水分条件下,盐分越大,水分生产率越大,7种处理中W2S2水分生产率达到最大,而其产量较对照并未显著减小,生育期提水量占需水量的17.73%。本研究对进一步理解作物在"上干下湿"的土壤水盐胁迫下充分利用土壤剖面深层水分来维持上层根系生存和提高水分生产率具有科学价值。     

掌叶覆盆子种子繁殖力关键影响因素分析

掌叶覆盆子野外种群的更新由根蘖繁殖完成,实生苗罕见,种子繁殖力低。本研究从掌叶覆盆子种子的结实特性、采种期、储藏时间、母树来源、激素含量变化与种子萌发等方面对其种子繁殖力影响因素进行了全面的分析。结果表明:掌叶覆盆子种子数量充足,群体内结实特性保持着一致性;当年熟果种子活力达到75.33%,储藏时间超过1年种子活力迅速下降且发芽率为0;不同母树来源种子发芽率无差异;青果、黄绿果时期种子活力和发芽率都较低,熟果和过熟果实种子活力达最高值且基本一致,但熟果GA 3/ABA比值最大,发芽率最高;不管是否添加外源激素,随着果实过熟程度加深,种子发芽率迅速下降,种子休眠程度也随之加深;酸蚀和激素可有效破除休眠,提高发芽率。采种时间、储藏时间、酸蚀和赤霉素催芽等是影响掌叶覆盆子繁殖力的关键因素。     

太岳山油松人工林土壤质量随林龄的演变特征

为探讨土壤质量随林龄的演变特征,以山西太岳山40,60,80年生油松Pinus tabuliformis人工林为研究对象,采用综合指数评估相关的土壤质量状况。结果表明:随着油松人工林龄增加,土壤含水率显著增加,而土壤容重则显著减小;而0~10 cm土层的有机质、全氮、速效钾、铵态氮、硝态氮、有效磷质量分数增加最为显著;80年生油松林的土壤微生物碳氮质量分数分别在10~30 cm和0~20 cm土层显著大于60年生和40年生油松林,而不同林龄油松人工林的土壤质量综合指数为0.568（80年生油松纯林）> 0.500（60年生油松纯林）> 0.363（40年生油松纯林）。说明随着林龄的不断增加,土壤微生物量碳氮质量分数和理化性状得到了提高和改善,太岳山油松人工林的土壤综合质量也不断提升。     

Protein deficiency and tribal warfare in Amazonia: new data

Increasing numbers of anthropological studies about native Amazonian warfare and demographic practices attempt to explain these phenomena as competition over or a response to scarce game animals and other sources of high-quality protein. Recently completed field research among the Yanomam? Indians living at the Venezuela-Brazil border indicates that their protein intake is comparable to that found in highly developed industrialized nations and as much as 200 percent more than many nutritional authorities recommend as daily allowances. Recent data on other Amazonian tribes likewise fails to indicate a correlation between protein intake and intensity of warfare patterns.     

Paleocirculation of the deep north atlantic: 150,000-year record of benthic foraminifera and oxygen-18

Benthic foraminiferal faunas in a piston core from 3331 meters at 44 degrees N on the Mid-Atlantic Ridge show striking variations in the relative abundance of species. Uvigerina peregrina, which is broadly distributed today in the South Atlantic and in the Pacific in water that has been long isolated from the surface, is absent in the North and Equatorial Atlantic at depths occupied by highly oxygenated North Atlantic deep water. This species dominated the fauna at this site for much of the past 150,000 years. It is suggested that North Atlantic deepwater production was much reduced or eliminated at times of Uvigerina peregrina abundance, as a result of cooling and stratification of the Norwegian Sea surface, coincident with the times of the southward migration of the polar front in the North Atlantic.     

The Ischigualasto Tetrapod Assemblage (Late Triassic, Argentina) and 40Ar/39Ar Dating of Dinosaur Origins

(40)Ar/(39)Ar dating of sanidine from a bentonite interbedded in the Ischigualasto Formation of northwestern Argentina yielded a plateau age of 227.8 +/- 0.3 million years ago. This middle Carnian age is a direct calibration of the Ischigualasto tetrapod assemblage, which includes some of the best known early dinosaurs. This age shifts last appearances of Ischigualasto taxa back into the middle Carnian, diminishing the magnitude of the proposed late Carnian tetrapod extinction event. By 228 million years ago, the major dinosaurian lineages were established, and theropods were already important constituents of the carnivorous tetrapod guild in the Ischigualasto-Villa Unión Basin. Dinosaurs as a whole remained minor components of tetrapod faunas for at least another 10 million years.     

渭北旱塬两种类型农林复合经营生态系统环境效应评价

为研究农林复合经营生态系统的营造及其人为管理对当地环境产生的影响,在实地监测和调查分析的基础上,运用多级模糊综合评判-灰色关联优势分析复合模型,对渭北旱塬2种主要类型农林复合经营生态系统(以苹果-农作物间作为主的T1型和以花椒-农作物间作为主的T2型)的环境效应进行了评价与对比研究。结果表明,土壤、径流水体、农副产品环境污染状况,T1、T2均为Ⅰ级;当前社会经济效益T1(Ⅱ级)高于T2(Ⅲ级);生态环境效应T2(Ⅱ级)优于T1(Ⅲ级);综合环境效应T1、T2均为Ⅰ级。在此基础上运用灰色关联优势分析进一步区分T1、T2综合环境效应的优劣,T1、T2与理想状况参考数列的关联度分别为0.6670、0.6674,T2的综合环境效应优于T1。从综合环境效应和生态可持续发展来看,以花椒-农作物间作为主的T2型优于以苹果-农作物间作为主的T1型。